1. Field of the Invention
The present invention relates to rotors and, more specifically, to a flywheel magnet rotor assembly and a method of making the same.
2. Prior Art
There are numerous different types of flywheels, magnet rotors and commutators known in the art. U.S. Pat. No. 4,710,659 to Takano et al. discloses a resin molded rotor for a magneto generator having a magnet, a molded resin disk, and a ferromagnetic metal core having two poles integrally formed on the core and a pair of bridges connecting a first magnet pole receiving portion with a second magnet pole receiving portion.
U.S. Pat. No. 4,390,804 to Orova et al. discloses a magneto generator having a magnet wheel with two pole pieces embedded in a body of a non-magnetic material that defines the shape of the wheel having fan blades. The magnet is fastened between pole plates with each of the pole faces of the magnet abutting one of the pole plates.
U.S. Pat. No. 4,241,620 to Pichl et al. discloses a balance wheel made of non-ferrous metal having a magnet and a ring of magnetic material.
Various different problems exist in the prior art. A principal problem with prior art magnet rotors is that their relatively heavy weight make small portable engine driven tools relatively heavy.
Another principle problem with prior art relatively light weight rotors is that ferromagnetic cores which are also used as pole plates result in magnetic loses through shunting of magnetic flux and thus, the loss of potential energy.
Another problem with prior art devices is that engine driven tools having relatively light rotors generally have inadequate inertia which produces engine torque fluctuations and increases cranking effort.
Another problem with prior art devices is that engine driven tools having relatively light rotors have inadequate internal mechanical strength which can result in bursting of the rotor at high speeds such as in excess of 25,000 RPM.
Another problem with prior art rotors is that it is preferable to fasten a rotor to a shaft with a tapered hub, but light weight rotors of the prior art require separate inserts to provide a tapered hub thus, increasing assembly and manufacturing costs and time.
It is therefore an objective of the present invention to provide a light weight rotor especially suitable for small portable engine driven tools with sufficient inertia to smoothen engine torque fluctuations, ease cranking effort and reduce the tool weight.
It is another objective of the present invention to provide a light weight rotor having a can shaped core for containing a magnet, a counterweight and pole shoes, for providing mechanical integrity of the rotor, and thereby for preventing bursting of the rotor at high speeds.
It is another objective of the present invention to provide a light weight rotor having a tapered hub integral to a stamped structural core and thereby lower manufacturing costs and assembly time.
It is another objective of the present invention to provide a magnet rotor with substantially small internal magnetic losses.